Copper fungicide



Patented Jan. 22, 1935 l UNITED STATES PATENT'OFFICE COPPER FUNGICIDE Alwyn 0. Sessions, New Brunswick, N. 1., assignor to Stanco Incorporated 4 I No Drawing. Application October 3, 1931,

Serial No. 566,785

8 Claims. (Cl. 167-16) This invention relates to a new fungicide and I arrived at the following conclusions which are more specifically to a fungicide comprising a comimportant for the right selection of the relative plex copper ammonium silicate compound. The amounts of constituents:'

' word compound" is used throughout the speci- 1. When the pH of the mixture is neutral a defication and claimsinabroad sense to mean either crease of the pH value increases the amount of 5 a definite chemical compound or a mixture of soluble copper. definite chemical compounds or any other com- 2. As the pH of the mixture is increased above plex association of the several chemical groups 7.5 by the addition of more ammonium hydroxide concerned. The invention also includes the there is a corresponding increase in the amount of 10 method of preparingthe fungicide and will be' soluble copper. 10 fully understood from the following description. 3. As the relative proportion of ammonia to Copper has long been employed as a'fungicide the sodium silicate is increased in the mixture and while its toxicity is attributed wholly to the the pH range at which the copper can be held in copper in solution, it must be applied to plants an insoluble form becomes narrower.

in an insoluble form. Through the action of the 41 As the relative proportion of sodium silicate l5 plant, the fungus, or atmospheric agencies, a to ammonia is increased in the mixture the pH suflicient amount of copper is brought into solurange at which the copper can be held in an intion to d stroy the fungous spore. If the copper soluble form becomes wider. compound is too unavailable its fungicidal efli- 5. When a relatively high proportion of amciency may be too low to control the disease; if monium hydroxide is employedinmaking the cop- 20 too available, it will be toxic toward the plant per ammonium silicate complex, the buffering acon which itisused'. Since copper salts are readily tion of the complex is lowered and a relatively soluble in slightly acid solutions and very insolusmall amount of acid will bring a relatively large ble under alkaline conditions, it is highly probaquantity of copper into solution.

ble that the hydrogen-ion concentration (pH) of 6. When a relatively high proportion of sodium 25 the protoplasm of the plant and'spore as well as silicate is used in the preparation of this copper the acidity of the atmospheric moisture, plays complex, the bufiering action is high and a relaan important role inthe availability of the copper tively large amount of acid is required to bring compound employed. Since we have no means copper into solution.

of adjusting these external factors influencing the 7. As the'relative proportion of ammonium hy- 80 availability of the copper, I have prepared a copdroxide used increases, the per cent of copper in, per salt in which the availability of the copper may the complex increases. v be adjusted and which-contains sufiicient buii'er- 8. As the relative proportion of sodium siliing power to be relatively unaffected by slight cate employed is increased, the. per cent of coppH changes in the surrounding media. In other per in the complex is decreased. words a compound has been prepared in which the It is evident from the above discussion that in availability of the copper can be adjusted so this copper ammonium silicate complex we have as to be harmless to the plants on which it is apa compound carrying insoluble copper, in which plied, yet suiilciently available to destroy the disthe buffering action and the availability of cop- 40 case in question. per may be adjusted so as to be harmless to the 40 I discovered that by adding to a sodium silicate plant and yet sumciently toxic to destroy the solution ammonium hydroxide and a copper salt, disease. preferably copper sulfate, insoluble copper am- The preparation of this new copper complex momum silicate gels can be prepared which have w l be t illustrated y h f wi xampl 4.5 a high degree of stability. The pH value of the 50 po of pp te is di so v d in 50 almixture greatly alters the nature of the gel lens of a 55 p nds f ium silicate (water and the concentration of copper therein. It, was glass) is ,dilllted with water to w y' llon found that with careful adjustment of the propor- Into this diluted sodium silicate solution is stirred tions of the chemicals involved, so that the re- 17.5 pounds of an a m w r D r. 0-

sulting mixture is neither too acid nor too whi h had P v y been diluted w Water 150 alkaline, practically all of the copper could be appr mflte y'ilfl gallons. While the 50 gallons brought into an .insoluble form. The relative of copper sulfate solution are being rapidly stirred availability of the copper can be adjusted by varythe 40 gallons of the sodium ammonium silicate ing the proportions of ammonium hydroxide and solution are slowly added. An insoluble copper (I sodium silicate employed. By experimentation ammonium silicate gel forms, which is robin egg blue in color. The mixture is filtered through lawn cloth, the precipitate washed free of excess soluble salts and stored in barrels or drums to later be diluted and used as a spray.

As stated above, the ratio of ammonium hydroxide to sodium silicate may be altered but it is essential that the pH value of the final concentrated mixture obtained from copper sulfate, ammonium hydroxide and copper silicate, is not greater than 8.0 or lower than 6.5. Ifthe mixture is made more basic than this by increasing the ammonium hydroxide, or more acid by decreasing the ratio of the alkalies to the copper sulfate much of the copper will remain in solution. Samples from the mixture are taken from time to time-as the sodium ammonium silicate is added-filtered and the pH value of the filtrate determined. When a neutral or slightly alkaline reaction is reached, the mixing is stopped, the mixture filtered and the precipitate washed.

The insoluble copper ammonium silicate compound can also be prepared by adding ammonium hydroxide to a solution of copper sulfate until the resulting mixture reaches a pH value of approximately 6.5 and then adding sufficient sodium silicate to bring the mixture to neutrality or to make it slightly alkaline, being careful that the pH value does not go above 8.

Another method of preparing my complex compound is to add sodium silicate to a solution of copper sulfate until the pH value of the mixture approaches 6.8 and then add the ammonium hydroxide until the mixture is neutral or slightly alkaline, being careful not to exceed a pH value of 8. An insoluble copper silicate can be prepared by adding sufilcient sodium silicate to the copper sulfate to bring the mixture to a pH of 7.0-7.5. But the copper concentration of such a paste is low.

In the modified processes, like in the above example, the final mixture is filtered and the precipitate washed with water until free of excess salts.

Instead of copper sulfate other soluble copper salts, such as copper chloride, etc., may also be The complex copper ammonium silicate compound prepared by any of the various modifications of my process has proven in field and laboratory tests to be an excellent fungicide when incorporated with water and used as a spray or when used as dust on agricultural plants.

When properly prepared as described above the spray or dust has proven substantially harmless to plants on which it was used. Field and laboratory studies have shown this new complex to be no more harmful towards apples, peaches, sunflowers, tomatoes, potatoes or bean foliage than Bordeaux mixture at the same copper concentration. Laboratory tests and field experiments have also shown this compound to be highly effective as a fungicide against fungi such as Ventura inaequalis, Cylindros orium pomi Brooks, Pestalotia macrotricha. Its fungicidal value and the availability of the copper can be regulated according to the plant and fungus, during its manufacture, according to the principles above enumerated. When used for spraying the final spray preferably contains from 0.03% to 0.40% of copper. -When used as dust it may be used either in concentrated form or mixed with say 4 times its weight of. a filler.

The powder or dust form of this fungicide has proven highly effective as a seed disinfectant. In tests where its efliciency was compared with some fifteen different commercial materials, it

ranked second to the highest in controlling the Spray program and material used percent Percent" leaves Spray No. savmday and leaves clean sequent sprays m] b Delayed dormant Pro-pink Pink Petal on w 2$ 1 Oil Cresylic Lime sulfur l-i0 Lime sulfur l-40.. Flotation sulfur l0 Flotation sulfur 10 2.4 07. 0

acid 5% 100 g lbs. to 100 Lead aisenate 3 Lead arsenate 3 lbs.-i00 lbs.l00 gals. 2 None... Oil 3% Copper Copper ammo- Copper ammonium Copper ammonium 0. 4 99. 5

ammonium sillnium silicate silicate 0.12% On. all cats 0.06% Cu. cate 0.25% Cu. 0.25% Cu. Lead iii-senate 3 Lead arsenate 3 lbs. to 100 gals. lbs. to 100 gals. 8 Check. No spray app ied 47 53 Paste form of the spray was employed.

used in the preparation of the complex copper compound. The copper ammonium silicate pastes formed by these methods differ somewhat in the percentage of the various components and as a consequence also in their buffering action to-' wards acids and bases. The mixture is filtered and the paste washed free of soluble salts. When the fungicide is applied to plants it is diluted with water to the desired strength.

My complex copper compound may also be used as fungicide in powder form. For this purpose the precipitate obtained by any of the above described methods is dried, ground and sieved or air floated. An inert filling material such as talc or powdered clay may be added to the complex copper compound.

Experiments were conducted to determine the efllciency of the copper ammonium silicate as a seed treatment for controlling the fungi responsible for seed decay and the damping-off of cucumbers. The seeds were treated by shaking them with the powdered form of the fungicide and screening off the dust that would not adhere to the seed.

While but 3.6 per cent of the plants from the untreated seed survived, the attack of these organisms, 54 per cent of the copper ammonium silicate treated seed germinated and produced plants. In comparative tests with 14 other recognized seed disinfectants, the copper ammonium silicate ranked fourth to the highest in efllciency against these fungi.

In'other experiments pea seeds were treated, before they were planted, with the powdered form of the copper ammonium silicate and fourteen other recognized seed disinfectants to determine the comparative efliciency of these materials in controlling the fungi responsible for seed decay of peas. Only seven per cent of the with this material survived. with the third best I material employed there were only 25 per cent of the seeds planted which did not decay.

This invention is not to be limited by any theory or'the particulars given by way of illustration but only by the following claims in which it is my intention to claim all novelty inherent in the process.

I claim:

1. The method of preparinga complex fungicidal copper compound which comprises admixing a copper salt, sodium silicate and ammonia in aqueous solutions in such proportions as to adjust the availability of the copper in the complex so that the latter becomes harmless to the plant being sprayed yet toxic to the organism producing the disease in question.

2. The method of preparing a complex fungicidal copper compound which comprises adding ammonia to an aqueous solution of sodium silicate and mixing so much of the solution thus obtained with an auqeous solution of copper sulfate that the pH value of the mixture be substantially between the approximate limits of 6.5 and 8.

3. The method of preparing a complex fungicidal copper compound which comprises admixing ammonia to a solution of copper sulfate until the resulting mixture reaches a pH value of approximately 6.8 and then admixing sufilcient sodium silicate to bring the mixture to neutrality or make it slightly alkaline without exceeding a pH value of about 8.

4. The method of preparing a complex fungicidal copper compound which comprises admixing sodium silicate to a solution of copper sulfate until the pH value of the mixture approaches 6.8 and then adding ammonia until the mixture is neutral or slightly alkaline without exceeding a pH value of about 8.

5. The process according to claim 1 in which the mixture is filtered and washed with water until the free of inorganic salts. I

6. The method of destroying fungi which comprises spraying on the plant diseased with fungi a fungicide obtained by admixing a copper salt, sodium silicate, and ammonium hydroxide in aqueous solutions and in such proportions as to render the copper sufficiently available to'destroy 8. A fungicide, comprising a complex copper ammonium silicate compound.

A. C. SESSIONS. 

